1979 Volume 70 Issue 3 Pages 291-299
Urinary oxalate excretion of stone-formers (93 cases) and none stone-formers (86 cases) were determined using the new method reported previously. In none stone-formers, the amount of urinary oxalate excretion was estimated to be 29.5±12.6 (S.D.) mg/24hrs, which is almost the same value as measured by the other methods, and ranged from 4.3 to 54.7mg/24hrs with our new method. In stone-formers, although most of them failed within the normal range their average value, 33.7±14.5 (S.D.) mg/24 hrs, showed a significant increase (p<0.02) compaired to none stone-formers. Among them, apparently increased values over 55mg/24hrs were found in 17 cases (18.3%).
In both groups (stone-formers and none stone-formers) there was no difference between the sexes in the amount of urinary oxalate excretion. However, the male stone-formers showed a significant increase of the amount compaired to the male none stone-formers, but not in the females. This will indicate that other contributing factors or mechanisms exist in the stone formation in the female stone-formers.
In both groups there was no correlation between ages and renal functions indicated by creatinine clearance upon the amount of urinary oxalate excretion excluding a child.
It was found that the stone-formers of calcium oxalate excreted more urinary oxalate than the stone-formers of calcium phosphate. This may mean that urinary oxalate itself has some roles in the stone formation mechanism for calcium oxalate calculi.
Since there was no difference between both groups in concentration of urinary oxalate, the difference in the amount of urinary oxalate excretion is considered to be dependent on urinary volume, namely stone-formers having larger urinary volumes than none stone-formers. To elucidate this phenomenon all of the cases were divided into 4 groups according to urinary volume in steps of 800ml. In both groups of the stone-formers and none stone-formers, concentrations of urinary oxalate decreased with increase of urinary volumes, however the amount of urinary oxalate excretion increased with the urinary volumes and the degree of this increase was significant in the stone-formers. From these results it is considered that urinary oxalate excretion is dependent on the urinary volume and this mechanism occurs in renal tubular abnomality in oxalate reabsorption or excretion without disturbance of renal function.
In the cases of apparently increased excretion of urinary oxalate, it is suspected that there are absorptive abnomality of oxalate or its precursors, or abnormal endogenous production of oxalate.
From these studies presented here, it is useful in clinical investigations for stone formation that the amount of urinary oxalate excretion can be determined in simple procedure using our new method. In fact two cases of primary hyperoxaluria were diagnosed by measurment of markedly increased urinary oxalate excretion by this method during this study.
